Can two vessels have same MMSI?

Can two vessels have same MMSI?

The messages also include a nine-digit Maritime Mobile Service Identity (MMSI) that is supposed to be unique to each vessel. This means that all throughout the oceans, multiple vessels are simultaneously broadcasting the same MMSI number, making them indistinguishable from one another without closer inspection.

Can you describe the 2 classifications of AIS?

There are two types of Class B AIS, those using carrier sense Time-Division Multiple Access (CS-TDMA) technology and those like the Class A using Self-Organizing Time-Division Multiple Access Technology (SO-TDMA).

Is AIS and MMSI the same?

Maritime Mobile Service Identity (MMSI) is a unique 9 digit number that is assigned to a (Digital Selective Calling) DSC radio or an AIS unit. Similar to a cell phone number, your MMSI number is your unique calling number for DSC radios or an AIS unit.

What are the 3 dynamic information of an AIS?

AIS transmits, automatically and at set intervals, dynamic information relating to the ship’s course, speed and heading; static information related to the ship’s name, length, breadth; and voyage-related details such as cargo information and navigational status (e.g. underway or at anchor).

What is the difference between Class A and Class B AIS?

The main difference between Class A and Class B units is the power output, Class B transmits at 2W, giving a range of between 8-10 miles, whilst Class A transmits at 12.5W giving a much larger range.

What vessels are required to have AIS?

The following vessels are required to install and use a Class A AIS transponder: All commercial vessels of 65 feet or more in length (except as defined below) Towing vessels of 26 feet or more in length and more than 600 horsepower. Vessels certificated to carry more than 150 passengers.

What is Class A and Class B AIS?

Class A AIS vs. Class A AIS transponders (SOLAS Compliant) operate using Self-Organizing TDMA (SOTDMA) broadcast mode and transmit at a power level of 12.5 watts. Class B AIS transponders operate using Carrier-Sense TDMA (CSTDMA) broadcast mode and transmit at a power level of 2 watts.

What is the difference between AIS Class A and Class B?

Do I need an MMSI number for AIS?

MMSI numbers are transmitted over a Digital Selective Calling (DSC) radio or Automatic Identification System (AIS) unit. Each vessel should have only one MMSI.

What is the basic principle of AIS?

The principle of AIS is to allow automatic exchange of shipboard information from the vessel’s sensors – inputted static and voyage related data – between one vessel and another and between a vessels and a shore station(s).

What is a Class A transponder?

Class A AIS transponders are mandated for vessels over 300 tons, fishing vessels over 15m, passenger carrying vessels and for SOLAS Convention. AIS Class B transponders are for recreational craft installation and have a transmission power of 2W (range of about 10 miles). They have a transmission power of 5W.

What is the maximum range of AIS?

AIS enables authorities to reliably and cost effectively monitor fishing vessel activities along their coast line, typically out to a range of 100 km (60 mi), depending on location and quality of coast based receivers/base stations with supplementary data from satellite based networks.

How many messages per second can an AIS decoder send?

When running on multiple logs concurrently (8 threads is a good number on modern hardware) 12M+ NMEA messages per second is possible. During testing it was also found that most of the time was spent on the 6bit nibble packing and unpacking, not the file IO.

When to use multiple slots in AIS decoder?

The transmission of one packet is called a slot, during which time exactly 168 bits of data can be sent. If a NMEA sentence contains more than 168 bits, multiple slots are used, the complete message being re-assembled by the AIS receiver.

Is there a C + + decoder for AIS?

Also please, checkout https://github.com/aduvenhage/ais_beast for an attemp to make a faster (C++ only) decoder. The decoder is designed to work off of raw data (processed in blocks) received from, for example, a file or a socket.

How is meta data reported in AIS decoder?

The meta data is provided as a header and a footer string to the user via one of the pure virtual methods on the decoder interface. For multi-line messages only the header and footer of the first sentence is reported (reported via ‘onMessage (…)’).